In a known rotary mower of this type (German Patent document-Gebrauchsmuster-No. 69 34 709) the retaining pin is secured by a riveted joint directly to the leaf spring.
In order to ensure adequate wear resistance of the retaining pin, it is necessary to harden it by a case-hardening process. However, the rivet head must remain deformable in order to be able to make the riveted joint. For this purpose the part from which the rivet head is subsequently shaped must be masked from the actual hardening process during the case-hardening.
This mode of production of the retaining pin has proved to be highly onerous. Disadvantages have also been experienced because the different hardening zones result in internal stresses particularly in the case of conically shaped retaining pins which are additionally provided with a cylindrical head part.
During the operation of the rotary mower the retaining pin is subject to more or less powerful shock stresses. These frequently cause pieces of material to break away.
More specifically, prior art arrangements in which the retaining pin itself must be deformed by a riveting process have led to difficulties in large measure due to the fact that the deformable head had to be subjected to a different treatment from the body of the retaining pin and this created a threat of danger to the operator, to the machine and to anyone in the vicinity of the mower.